Oil Spill on the Wild Harbor Marsh by John M. Teal and Kathryn A. Burns

The Cape Naturalist: Vol 1 No 1

June, 1972

Oil Spill on the Wild Harbor Marsh

by John M. Teal and Kathryn A. Burns

The oil spill at West Falmouth which resulted from the grounding of a fuel oil barge in September 1969, is probably the best studied such accident in the world. Within one week of the spill scientists at Woods Hole Oceanographic Institution began studying the lethal effects of the oil on bottom animals. Observation of changes in abundance and distribution of animals and chemical characteristics of the oil remaining in the sediments have continued to the present.

Our work has dealt with the effects of the oil on the salt marshes of the Wild Harbor river onto which the oil was carried by a storm a few days after the spill. In spite of large numbers of dead estuarine animals, the immediate, apparent effect of the oil on the marsh itself was minimal. Marsh grasses were already seasonally brown when oiled. Dead fish and mussels were found on the marsh surface but throughout the first winter after the spill the marsh was fairly normal in appearance. During the following spring the effect of the oil became apparent.

Grass did not sprout on the oiled marsh as it did on the unoiled portions which turned green as usual. A small growth of green algae, along with a scattering of Salicornia (saltwort) grew on the oiled surface but the sparse growth only emphasized how complete was the destruction. Plant production of the oiled portion was reduced to zero. What little production remained was not sufficient to offset the rate of decomposition. The latter was determined by measuring carbon dioxide production resulting from the respiratory activity of all marsh organisms. Since only a few minute soil animals remained in the marsh, most of this activity was due to bacteria. Even this bacterial activity on the oiled marsh was only one quarter of that on the nearby healthy marsh.

We analyzed mud and marsh organisms collected the summer after the spill and found measurable quantities of oil in all marsh animals and plants living on or next to the dead marsh. We also found the contaminated mud to contain less oil (170 ppm-parts of oil per million parts of mud by weight) in areas on which Salicornia grew than in areas where all plants were dead (3000 ppm). The oil had penetrated down into the mud more than three feet and had also spread laterally in small amounts (30 ppm), into adjacent, originally unoiled marsh. The marsh grass growing where there was lateral spreading didn’t show any effect of oil.

Apparently, 30 ppm of oil is insufficient to kill plants. One hundred seventy ppm will kill marsh grasses but not all marsh plants, while some higher amount will kill all plants. Unpolluted salt marsh mud contains about 5 ppm of hydrocarbons or oils which come from natural sources, the plants themselves. The amounts of oil in the organisms seemed to be related to how close they lived to the mud on which the oil settled. Algae on the mud contained several hundreds of parts per million while fish and eels that visited the marsh only to feed contained only eighty or less. However, a herring gull that was feeding on animals killed by the spill had accumulated 550 ppm in its muscles and brain. We do not know what the effects of such accumulations may be but do not think they contribute to the organisms’ well being.

We studied and are continuing to study the recovery of the marsh. During the second summer after the accident, more Salicornia grew and some marsh grass began to grow on the oiled area. The grass was greener that that growing on unaffected, nearby marsh due to the large supply of plant nutrients which had been released from the killed grass and held in the mud over the winter. Animals returned to the marsh also. A few fiddler crabs tame back. C1amworms were fairly abundant in a few areas and live mussels were found in the mud. Mummichogs moved in with the tides. We cannot say, however, whether they were actually feeding in the oiled marsh. We know very little concerning the reasons for the return of the animals. Oil remains in the marsh in large amounts, almost as much as was there immediately following the spill.

Perhaps the composition of the oil has changed with the most toxic parts evaporated or gone into solution, at least from the surface layers of the mud. Or perhaps there has been a selection for individuals that are more resistant to oil than the average and it is only these more resistant types that are now living on the marsh. These questions are occupying us at the moment and we hope to have at least partial answers soon.

Whatever the reasons for the recovery, the recovery itself illustrates the tough nature of the salt marsh eco-system. Even though it may be subject to a great deal of insult from humans and human products, it can survive. For the insulted Wild Harbor marsh it is too early to say more than that it is tough and it is recovering.

The mud is still full of oil and it would appear that it will stay full of oil for many decades. We can see little indication of change in either amount or composition of oil in the deeper marsh sediments.

How complete will the recovery be? Has the marsh been made more resistant to another spill by the first or made more susceptible? Would a different sort of insult, sewage pollution or a natural event as an unusually cold winter, damage the once oiled marsh more than one that has never been subjected to a spill? It is possible we may never know the complete answers to all these questions but we have probable answers. The damage affected only a relatively few acres of marsh in one small bay, but it has provided a great deal of information about how marshes are affected by oil and hopefully will give us a great deal more about how they recover.

Background references:

Burns, Kathryn A. and j. M. Teal, 1971, “Hydrocarbon incorporation into the salt marsh ecosystem from the West Falmouth oil spill” W.H.O.1. Technical Report 71-69. Blumer,

M., j. Sass, G. Sauza, H. Sanders, F. Grassle, and G. Hampson, 1970, “The West Falmouth oil spilL” W.H.O.1. Technical Report 70-44. Blumer, M., et al 1972, “The West Falmouth oil spill” W.H.O.1. Technical Report 72-20 I. Biology. II. Chemistry.

Blumer, M., et al, 1971, “A small oil spill” Environment 13, 1-12. Hampson, G. R. and H. L. Sanders, 1969, “A Local oil spill” Oceanus XV, 8-10.

DR. TEAL, a Senior Scientist in the Biology Department of the Woods Hole Oceanographic Institution, is the author, in collaboration with his wife Mildred, of the book “Life and Death of the Salt Marsh”, published by Little, Brown and Company. Mrs. Burns is a graduate student with the Massachusetts Institute of Technology/Woods Hole Oceanographic Institution joint program in biological oceanography.

Male Fiddler Crab Uca pugnax Photo by Robert Burns

1 Comment

  1. September 2, 2009 at 11:56 pm

    Cool site, love the info.

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